The big cookless starch-off took place shortly after dawn this morning. The contenders: instant quinoa flakes, instant pre-cooked rice, bean threads (cellophane noodles), and ramen. Each was placed into cold water and tested at 10', 20' and 30' by itself and with some coconut milk-based red curry sauce.
The quinoa reconstitutes within 10' into something that's edible but doesn't have great texture (whole quinoa, cooked, would be much nicer). It went better with the curry than I expected it might, but didn't really add anything to it. Still, it's good nutritionally, so I'm not ruling it out entirely.
The instant pre-cooked rice was still a little crunchy at 10'. By 20', there were only a few residual crunchy bits, and by 30', it was pretty well hydrated. With the curry, it provided some reasonable texture. Didn't really provide much flavor, but this is a reasonable cookless partner for the curry. Pretty useless nutritionally, but at least it's some carbs.
My high hopes for the bean threads were dashed at the first data point. At 10', it was not possible to bite through them at all, and at 20', they still could not be chewed. By 2 hours, they became edible, if distinctly chewy, and even at 6 hours, this hadn't changed. They had very little flavor of their own.
Ramen (thanks to Sarah's suggestion!) emerged as the clear winner. As others have pointed out, it's already cooked, and can be eaten right out of the package without cooking or rehydrating at all. At 10', it had a slight but not unpleasant crunch. By 20', it was pretty well rehydrated. The flavor worked reasonably well with the curry.
Ramen also seems pretty reasonable in terms of packaging (wrt trash and compactness) if one gets the plastic-wrapped kind without a bowl. Of the 3.1 oz package weight, only 0.2 oz is the (gross) flavor pack, so in my mind, it's a toss-up as to whether to open the package and remove the flavor pack in advance, or just to carry the unopened package and bring the flavor pack back as trash. Some have suggested crushing the ramen to reduce volume, but it's not clear to me that's going to have much of an effect. You'd have to crush it pretty finely to get the volume much lower than the "brillo pad" of noodles.
Thanks to Sarah and all for suggestions.
PS - I may still try couscous, but even if it's hydrated, it's still uncooked, so maybe not so great nutritionally?